The invention relates to a device for determining the mass of a fluid delivered by an injector, comprising a fluid-impermeable housing for fluid storage, the latter comprising an injector connection for connection, in particular of an inlet, of the injector and a fluid connection for feeding fluid in. The invention furthermore relates to a plurality of methods for determining the mass of fluid delivered by an injector.
The field of use of the invention extends to the development, functional testing and maintenance of fluid injectors, in particular gas injectors. Such injectors are used, for example, in the injection systems of diesel or petrol engines. One of the essential characteristic parameters of such an injector is the flow rate of fluid during its opening time, during which the fluid flow from the inlet to the outlet of the injector is made possible. The mass delivered per shot of such an injector is given from the opening time and the effective flow resistance of the injector during an injection process, together with the fluid properties, mathematically as an integral of the flow rate over this opening time, and in practice as an amount delivered within an injection process, as a characteristic and essential feature.
In the generally known prior art, measuring instruments based on the Coriolis force are used for flow rate measurement. In these instruments, a fluid flow is passed through a tube mechanically vibrating laterally, the inertia in conjunction with the density and the flow speed of the fluid contained in the tube influencing the resonance properties, particularly in the form of a phase shift along the tube. A corresponding phase offset can then be measured and used in order to quantify the fluid flow.
A disadvantage with this procedure is that the physical working principle requires a fluid flow formed constantly along the tube, or only having variations of orders of magnitude which are very much less than the axial extent of the tube. In the case of injectors whose opening times lie at low temporal orders of magnitude, for example hundredths of seconds or less, it is therefore necessary to generate quasi-homogeneous fluid flows by the respective injector carrying out a multiplicity of injections in rapid succession. The flow rate then measured by the Coriolis measuring instrument may be divided by the number of injections in order to obtain the flow rate, or the amount of fluid of an individual injection. A disadvantage with this is that no information about variation between individual injections (shot-to-shot variation) is possible, although it is precisely this device-specific parameter which is particularly relevant in practice.